This invention pertains to a method and apparatus employable in a wireless network communication system for delivering, in periodic transmission beacons, transmission budget information regarding available unused network communication bandwidth which is then competed for by communication stations that form part of a basic service set (BSS) of communicating stations in the system. More specifically, the invention relates to a modified form of beacon broadcast activity whereby the level of beacon-announced available bandwidth is calculated on the basis of prior, plural (rather than singular), inter-beacon, communication-transmission intervals.
In the description presented herein, certain letter acronyms are employed, and the following is a substantially full list of those acronyms and of their respective meanings:
APAccess PointSIFShort Interframe SpaceACKAcknowledgementACAccess CategoryRAReceiverAP MACAccess Point Media Access ControlTx TimeTransmit TimePHYPhysical (Layer)QoSQuality of ServiceMIBManagement Information BaseSTAStation
In a network communication system of the type generally outlined above, and according to conventional practice, periodic transmissions called beacons take place at regular intervals within a basic service set of communicating transmitter/receiver computers (stations). Each beacon transmission conveys information to the stations in the set regarding how much bandwidth will be available for access-competition in the next, successive (following the particular beacon transmission concerned) inter-beacon transmission interval.
Beacons are created and broadcast, normally, by one of the stations in a basic service set, which station is referred to as the access point (AP) station. It is this AP station which directly links with a network, and which, therefore, acts as a network port for all stations in the associated BSS.
Announced available bandwidth is referred to as a transmission budget. In general terms, the amount of bandwidth which is announced as being available (the transmission budget) by each beacon has its level, or size, calculated, as will be outlined below, by the AP station in accordance, to some extent, with immediate, prior transmission activity which has taken place in the system. That immediate prior activity typically includes the successful communication transmission activity which occurred during the last, single inter-beacon transmission interval. Thus, such immediate prior activity normally takes into account only the successful transmissions of those particular stations which gained and used bandwidth access in the last transmission interval.
In terms of gaining bandwidth access during a transmission interval in prior art practice, each station calculates what is known as its transmission limit, and the size of this limit bears upon both how a station seeks access, and how much access a successfully seeking station actually gets. Successful transmitting stations in the last transmission interval are permitted to calculate relatively larger transmission limits than are stations which did not transmit during the last transmission interval, and thus, stations seeking “new entry” to available bandwidth are consequently placed at a competitive disadvantage. The shorter the transmission interval, of course, the fewer in number, usually, will be the collection of stations that successfully transmit during that interval. As a result, there tends to be, in relation to transmission interval length according to prior art practice, an inversely related back-up size, or line-up, of stations awaiting access.
Given the fact that, in accordance with such conventional practice, a new transmission budget is calculated for each successive beacon transmission, it is well recognized by those skilled in the relevant art, that the shorter the interval between successive beacon transmissions, the more likely it will be that regular communication back-ups, like those just mentioned, will occur with respect to newly active stations which become ready for transmission-budget access.
According to the present invention, such back-ups can be significantly reduced, and two different, but commonly grounded, ways of dealing with this kind of back-up situation are specifically proposed by this invention, and are described herein. Both involve using a larger-than-single, prior, inter-beacon transmission-interval activity history as the basis for calculating transmission budget, and each involves broadcasting to BSS stations this differently-calculated transmission budget in slightly different formats. By so calculating the transmission budget, and since it is likely that more stations' activities will be accounted for in the calculation, since the “calculation” interval is enlarged to include plural, normal inter-beacon transmission intervals, a key contributor to conventional back-ups is significantly subdued.
The various features and advantages which are offered by the invention will become more fully apparent as the detailed description which now shortly follows is read in conjunction with the accompanying drawings.